1. Technical Field
The present invention relates to a semiconductor light emitting element coupled with optical fiber in which emission of a semiconductor element is outputted from an optical fiber.
2. Background Art
In optically coupling an edge emitting type semiconductor laser and an optical fiber for instance, optical means such as lens are used in general. The optical means such as lenses or the like can converge a diameter of a broad output beam of a semiconductor laser to a narrow one to enable to enter in the optical fiber with ease. As the result of this, a coupling loss between the semiconductor laser and the optical fiber can be suppressed.
However, in optically coupling a semiconductor laser and an optical fiber by use of optical means such as lens or the like, a plurality of lenses are required to be aligned with extremely high precision. Accordingly, an alignment takes a long time to result in increasing manufacturing costs.
As the means for annulling complication of the alignment, a method in which an emitting element and a light-propagating medium are directly coupled is disclosed in Japanese Patent Laid-open Publication No. HEI 5-134151. According to the above, a semiconductor laser and an optical waveguide are directly coupled to make unnecessary the complicated alignment, resulting in cost reduction.
In the disclosure of the aforementioned reference, however, the semiconductor laser and the optical waveguide are disposed in an intimate contact with each other on the same substrate. As the result of this, the optical waveguide dilates due to the heat of the semiconductor laser to cause the semiconductor laser and the optical waveguide to become off-axis, resulting in the likelihood of lowering light output.
Thus, in the existing semiconductor light emitting element coupled with optical fiber, temperature variation may cause a fluctuation of light output. In the case of a semiconductor laser of high output power being broad in an active layer in particular, close attention must be paid on the fluctuation of the light output.
The object of the present invention is to provide an semiconductor light emitting element coupled with optical fiber of which variation of light output is small even if there is a temperature variation and that operates with stability.
In order to achieve the above object, the present semiconductor light emitting element coupled with optical fiber is constituted in the following ways.
(1) A semiconductor light emitting element coupled with optical fiber comprises a substrate, an optical waveguide, a semiconductor light emitting element, and an optical fiber possessing a core of which end faces the other end of the core of the optical waveguide. The optical waveguide is disposed on the substrate and includes a core and a cladding layer covering the core. The semiconductor light emitting element is disposed on the substrate and possesses an outputting end-surface facing one end of a core of the optical waveguide. Here, the cladding layer sandwiches both side surfaces of the semiconductor light emitting element.
The cladding layer of the optical waveguide sandwiches both side-surfaces of the semiconductor light emitting element, thereby the semiconductor light emitting element being directly coupled to the optical waveguide. The semiconductor light emitting element being disposed on the substrate, in the neighborhood of an optical coupling (one end of the core of the optical waveguide) of the semiconductor light emitting element and the optical waveguide, the optical waveguide is not necessary to be solidly fixed onto the substrate. Accordingly, in the neighborhood of the optical coupling of the semiconductor light emitting element and the optical waveguide, between the optical waveguide and the substrate a gap can be formed.
As a result of this, even in the case where the optical waveguide is heated due to emission from the semiconductor light emitting element to result in dilation, in the neighborhood of the optical coupling with the semiconductor light emitting element, the optical waveguide is not pressed down on the substrate.
Accordingly, due to thermal expansion of the optical waveguide relative position between an output terminal of the semiconductor light emitting element and a core of the optical waveguide shifts less.
Further, the semiconductor light emitting element and the cladding layer of the optical waveguide being unnecessary to be connected, due to the dilation of the optical waveguide an optical coupling state fluctuates less.
As mentioned above, in the semiconductor light emitting element coupled with optical fiber involving the present invention, the temperature variation in the optical waveguide does not disturb a stable light output.
(2) A semiconductor light emitting element coupled with optical fiber comprises a substrate, an optical waveguide, a semiconductor light emitting element, and an optical fiber possessing a core of which end faces the other end of the core of the optical waveguide. The optical waveguide is disposed on the substrate and includes a core and a cladding layer covering the core. The semiconductor light emitting element is mounted on a base disposed on the substrate and possesses an output end-surface facing one end of a core of the optical waveguide. Here, the cladding layer sandwiches both side surfaces of the semiconductor light emitting element or the base.
The cladding layer of the optical waveguide sandwiches both side-surfaces of the semiconductor light emitting element or the base thereon the semiconductor light emitting element is mounted. Thereby, the semiconductor light emitting element and the optical waveguide are indirectly coupled. Accordingly, similarly with the case (1), a gap can be formed between the optical waveguide and the substrate, and the semiconductor light emitting element and the cladding layer of the optical waveguide are not required to adhere.
As a result of this, similarly with the case (1), in the semiconductor light emitting element coupled with optical fiber involving the present invention, the temperature variation does not disturb stable light output.
(3) A semiconductor light emitting element coupled with optical fiber comprises a substrate, an optical waveguide, a semiconductor light emitting element, and an optical fiber possessing a core of which an end faces the other end of the core of the optical waveguide. The optical waveguide is disposed on the substrate and includes a core and a cladding layer covering the core. The semiconductor light emitting element is mounted on a base disposed on the substrate and possesses an output end-surface facing one end of a core of the optical waveguide. Here, the cladding layer of the optical waveguide is solidly fixed on an upper surface of the base.
The cladding layer of the optical waveguide is solidly fixed on an upper surface of the base thereon the semiconductor light emitting element is mounted. Thereby, the semiconductor light emitting element and the optical waveguide are indirectly coupled. Accordingly, similarly with the case (1), a gap can be formed between the optical waveguide and the substrate, and the semiconductor light emitting element and the cladding layer of the optical waveguide are not required to adhere.
As a result of this, similarly with the case (1), in the semiconductor light emitting element coupled with optical fiber involving the present invention, even the temperature variation does not disturb stable light output.
(4) A semiconductor light emitting element coupled with optical fiber comprises a substrate, an optical waveguide, a semiconductor light emitting element, and an optical fiber possessing a core of which end faces the other end of the core of the optical waveguide. The optical waveguide is disposed on the substrate and includes a core and a cladding layer covering the core. The semiconductor light emitting element is disposed on the substrate and possesses an output end-surface facing one end of a core of the optical waveguide. Here, the cladding layer of the optical waveguide is solidly fixed on an end-surface of a side that does not face the optical waveguide of the semiconductor light emitting element.
The cladding layer of the optical waveguide is solidly fixed to the semiconductor light emitting element, thereby the semiconductor light emitting element is connected to the optical waveguide. Accordingly, similarly with the case (1), a gap can be formed between the optical waveguide and the substrate, resulting in dispensing with adherence of the cladding layer of the semiconductor light emitting element and the optical waveguide.
Accordingly, an optical coupling-state between the output end-surface of the semiconductor light emitting element and the core of the optical waveguide is not affected by the thermal expansion of the optical guide, to be constant. As a result of this, the temperature variation in the optical waveguide does not disturb stable light output.
(5) A semiconductor light emitting element coupled with optical fiber comprises a substrate, an optical waveguide, a semiconductor light emitting element, and an optical fiber possessing a core of which end faces the other end of the core of the optical waveguide. The optical waveguide is disposed on the substrate and includes a core and a cladding layer covering the core. The semiconductor light emitting element is mounted on a base disposed on the substrate and possesses an output end-surface facing one end of a core of the optical waveguide. Here, the cladding layer of the optical waveguide is solidly fixed to an end-surface of a side thereto the optical waveguide of the base does not face.
Accordingly, a gap can be formed between the optical waveguide the substrate, thereby the semiconductor light emitting element and the cladding layer of the optical waveguide being unnecessary to adhere.
Accordingly, similarly with the case (4), the temperature variation of the optical waveguide does not disturb stable light output.
(6) A semiconductor light emitting element coupled with optical fiber comprises a substrate, an optical waveguide, a semiconductor light emitting element, and an optical fiber possessing a core of which end faces the other end of a core of the optical waveguide. The optical waveguide is disposed on the substrate and includes the core and a cladding layer covering the core. The semiconductor light emitting element is disposed on the substrate and possesses an output end-surface facing one end of the core of the optical waveguide. Here, the optical waveguide is solidly fixed to the substrate in the neighborhood of the other end of the core and possesses a gap between the substrate in the neighborhood of one end of the core.
The existence of the gap, between the semiconductor light emitting element and the optical waveguide, decreases a shift of a relative position due to thermal expansion of the optical waveguide. Accordingly, the temperature variation in the optical waveguide does not disturb stable light output.